A BIM scientist has welcomed two recent reports in the scientific journal Nature recording how fisheries management and marine conservation have helped to reduce overfishing.
A recent Nature paper entitled “Rebuilding marine life” says that “substantial recovery of the abundance, structure and function of marine life could be achieved by 2050, if major pressures—including climate change—are mitigated”.
Writing in the current issue of The Skipper, Dr Ronán Cosgrove, BIM Fisheries Conservation Manager, says measures on management and conservation since the 1980s have boosted recovery to the point where two-thirds of large-scale commercial stocks are exploited at sustainable rates.
Cosgrove says that the number of marine species at risk of extinction has decreased while populations of marine mammals such as humpback whales and several seal species have significantly increased.
"The number of marine species at risk of extinction has decreased"
While it’s a case of much done and much more to do on the latter, climate change is the “critical backdrop against which all future rebuilding efforts will play out”, he says.
Drawing of the modified 100mm T90 codend by Dr Matthew McHugh
“Threats such as increased ocean warming, acidification, sea level rises, and ancillary impacts will need to be dealt with through effective mitigation of greenhouse gases and development of carbon capture and removal technologies,”he says.
Cosgrove says the latest edition of the Marine Institute Stock book includes a positive assessment of Irish fisheries.
The number of sustainably fished stocks rose from 33 in 2020 to 35 in 2021 with gradual progress towards long-term sustainable utilisation of the resource base since 2012, he says.
He attributes this to a variety of management measures and increasingly high-quality scientific advice from the institute.
Gear selectivity also helps develop sustainable fisheries, he says, such as increases in mesh sizes and introduction of large square mesh panels to reduce mortality in some fisheries.
Cosgrove records how BIM’s latest gear collaboration with industry has further boosted the performance of the highly selective T90 codend, a key gear measure in the Celtic and Irish Seas. The work was supported by the European Maritime and Fisheries Fund.
“Due to increased mesh openings, T90 consistently reduces catches of small fish. Thanks to increased water flow through the open meshes, greater quantities of larger market sized fish are swept into and retained in the codend,” he explains.
Testing of a new four-panel 100 mm T90 cod end design was led by BIM’s Daragh Browne, working with an Irish seiner and Cathal Boyle and colleagues at Swan Net Gundry.
The gear modification has been trialled in Canadian and Icelandic fisheries and was successfully tailored to the Irish seine net fishery with extensive design input from Swan Net Gundry, he says.
“Haddock is a key target species for seiners with additional monthly quotas allocated to this fleet,” he notes.
“Conducted on a self-sampling basis due to Covid restrictions, a comparison of the new T90 codend compared with a standard two-panel T90 codend demonstrated a 70% reduction in small grade haddock, and 157% and 133% increases in medium and large-grade haddock. Very few undersize fish occurred in either gear as expected with 100 mm T90 codends,”Cosgove says.
“While price data have yet to be analysed, large haddock are worth substantially more than small haddock meaning the new gear greatly assists in maximising the value of available quota,”he says.
Major reductions in small fish also reduces fishing mortality - leading to improved sustainability of the haddock stock.
The Nature papers are here
https://www.nature.com/articles/s41893-020-00668-1
https://www.nature.com/articles/s41586-020-2146-7
The MI stock book is available at www.marine.ie.
Cosgrove’s full report in The Skipper is here
https://theskipper.ie/good-news-for-fisheries-sustainability/
